The primary reason you may not be able to enter your dorm room is because something you may have saved in the Dorm Room is preventing Rec Room from being able to load you into your dorm. In the event that you find yourself in this sort of scenario, you may want to take advantage of "Safe Mode". This will allow you to access a default state of your dorm room.
Disclaimer: Saving your dorm room while in Safe Mode will overwrite your previous Dorm Room save. Do not do this unless it is a last resort, or you plan to delete your old Dorm Room for other reasons.
To access Safe Mode in VR
Once you have reached the profile select screen, click the shield icon on the top right. Read the disclaimer. To finalize, press the "Yes" button. The "Default Dorm enabled" message will pop up. Then, simply click on the profile you wish to access.
To access Safe Mode in Screen Mode
Once you have reached the main menu to log into the last profile you used to play Rec Room with, instead click on "Sign in to another Rec Room account". This will bring you to another page. Then, click on the "Safe Mode Off" text. Read the disclaimer. Once you confirm, the text will read "Safe Mode On" which means that Safe Mode is engaged. Then, simply click on the profile you wish to access.